Welding electrode



Patented July 24, 1934 1,967,872 WELDING ELECTRODE Gilbert E. Doan, Bethlehem, Pa.

No Drawing. Application July 14, 1930,

- Serial No. 467,977

3 Claims. (01. 219-8) This invention relates to a method and means metal by the gases surrounding it and thus imfor controlling the flow of liquid metals, and more proves the character of the weld. particularly to a method for increasing the rate The invention further consists in the new and of detachment of liquid globules or extent of flow novel features of operation and the new and of metals. The invention is applicable in arts original arrangements and combinations of steps where it is desired to increase either the extent of in the process hereinafter described and more flow of the metal or the extent of dispersion over particularly'set forth in the claims. the surface, Although the novel features which are be- In the art of metal casting, the invention pro lieved to be characteristic of this invention will vides for increasing the action of the metal in be particularly pointed out in the claims appenetrating narrow or restricted cavities and pended hereto, the invention itself, as to its obangles and causing the molten metal to fill the jects and advantages, the mode of its operation same sharply and completely. This is accomand the manner of its organization may be better plished by so reducing the surface tension .that understood by referring to the following descripthe tendency of the molten metal to retain a tion in which a particular commercial embodispherical contour is reduced to a minimum. ment thereof is disclosed. It will be understood, The invention also increases the extent of dishowever, that the processes and the steps thereof persion of the metal over a surface or the wetting may be modified in various respects without deeffector spreading, in brazing, welding or solderparting from the broad spirit and scope of the ing. In welding with an acetylene flame, for exinvention.

ample, the molten metal is caused to spread out In the following description and in the claims widely in a thin layer whereby the surface is the various steps in the process and the details more readily covered or a bond is extended even comprising the invention will be identified by to the capillary cracks between the parts to be specific names for convenience but they are inj0ined tended to be as generic in their application as so The invention may also be applied to arc weldthe art will permit. ing and provides for increasing the extent of flow In carrying out the present invention the speed of the metal in the weld and the rate of melting of of metal transfer is increased by causing the .the welding rod or electrode. The invention will molten metal on the end of the welding rod to be particularly described as applied to a welding m glo s and p from the at a p d rod by way of illustration. rate. This is accomplished by adding an ele- In arc welding with a metallic electrode or ment to the metal of the rod which lowers the surwelding rod, the speed with whichaweld is formed face tension of the molten metal and causes the has been found to depend upon-the rate of deglobules to drop from the end of the rod while tachment of globules from the metal of the rod they are of smaller size. to the weld as the metal becomes molten due If each drop remains on the rod along time to the heat of the arc. The liquid globulesconbefore dropping into the weld two disadvantages stitute the chief form of metal transfer. These arise: First, the formation of each succeeding globules form on the end ofthe rod and increase in globule is obstructed by the low heat conductivity size until they drop from the rod into the arc. of the preceding globule. Since the heat con- The molten metal itself is a poor conductor of 'ductivity of liquid steel is only a fraction as heat as compared to the solid metal of the rod great as that of solid steel, the globule effectuand accordingly interferes with the free transally blocks the flowing process and'retardsthe fer ofheat to the end of the rod and the rate of welding. Second, the adhering globule of steel melting thereof. Hence it is desirable to cause becomes contaminated at the high temperature the individual globules to become detached from of the arc before it falls in the weld. the rod at a rapid rate rather than to allow them In ferrous weldin s it has n fOlmd that to continue their growth. The present invention, a small quantity of antimony reduces the surtherefore, provides for increasing the speed of deface tension and permits the drops to fall from tachment of the globules and the rate of metal the rod when they are of smaller size, thereby transfer from the rod to the weld whereby the minimizing the interference of the molten metal speed of formation of the weld may be increased. with the heat transfer to the end of the rod it- Furthermore, the early detachment of each self. A comparatively small quantity of antiglobule and resultant rapid melting of the elecmony may be used for this purpose, for example, trode limits the degree of contamination of the less than 1%. This may be in the elemental form or in the form of an antimony compound such as the oxide and may be dispersed throughout the entire rod or it may be applied as a thin coating to the surface thereof or it may be placed in grooves or in a core. It has been found that less than 1% of antimony will produce a 50% increase in the rate of melting of a steel rod.

Various other elements'or compounds may also be employed for this purpose, although antimony has been found to be particularly satisfactory. For example, bismuth, gallium, lead, zinc, tellurium, tin, mercury as HgO and various other substances having surface tensions substantially less than the surface tension of the metal itelf are useful to a certain extent. Tellurium and bismuth in percentages less than 10% produce a substantial increase in rate of melting.

If a coating is used it may be applied to the rod in various ways. For example, the rod may be coated with water-glass containing a predetermined portion of the material. It is obvious also that the coating may be sprayed'upon the rod or may be applied electrically in which case a thin continuous film is obtained over the entire surface of the rod. In some instances it may be desirable to introduce the reagent into the are independently of the rod to affect the globule as above described.

The above process has been described as applied to welding rods, inasmuch as it is particularly applicable thereto. It is obvious, however, that the same principles may be applied to other arts, as for example, in metal casting. If the surface tension of the molten metal is reduced, the extent of flow of the metal is increased whereby it will more completely fill the mould, including the various corners and crevices therein. For this purpose a suitable proportion of antimony may be applied to the iron or steel,

or other metal which is being cast, the proportion desired effect. It is obvious, however, that it may be applied to other metals, in-which case a substance capable of lowering the surface tension of the particular metal involved ,may be incorporated therein.

The term metal flow is used herein to include the rate of flow as in welding rods and extent of flow as in casting, brazing, soldering, etc.

The term antimony as used in the claims is understood to refer to the atom whether in the form of elemental antimony or in an antimony compound.

Although certain novel features of the invention have been described and are pointed out in the annexed claims, it will be understood that various omissions, substitutions and changes in the-several steps of the process and in its operation may. be made by those skilled in the art without departing from the spirit of the invention.

What is claimed is:

1. A welding rod comprising iron as the principal constituent thereof, and having incorporated therewith a surface tension reducing agent in such small quantities as to substantially reduce the surface tension of the material of the rod when molten, without materially affecting the other physical properties of the iron in the rod, whereby, when the rod is subjected to a welding temperature, the drops of molten metal will more readily detach themselves from the rod onto the work, said surface tension reducing agent being selected from the group comprising tellurium, antimony, bismuth, gallium, mercury, lead, tin or zinc.

2. A welding rod comprising iron as the principal constituent thereof, and having incorporated therewith a surface tension reducing agent in such quantities as to substantially reduce the surface tension of the material of the rod when molten, without materially affecting the other physical properties of the iron in the rod, whereby, when the rod is subjected to a welding temperature, the drops of molten metal will more readily detach themselves from the rod onto the work, said surface tension reducing agent comprising antimony in' substantial amounts up to 1% of the weight of the rod.

3. The method of ferrous welding which comprises raising the work to a welding temperature, adding ferrous welding material to the weld,

adding also a surface tension reducing material in such small quantities as to reduce substantially the surface tension of the molten iron in the weld, without materially affecting the other physical properties of the completed weld, whereby the molten iron of the weld will spread more extensively over the work, said surface tension reducing agent being selected from the group comprising tellurium, antimony, bismuth, gale lium, mercury, lead, tin or-zinc.

GILBERT E. DOAN. 

